Lift-and-place apparatus

ABSTRACT

A material-handling apparatus includes a frame, first arms pivoted to the frame for rotation, and second arms pivoted to the first arms for rotation. A picking device is pivoted to the second arms. A rotational control device including a cam is operably connected to the first and second arms for oscillating the first and second arms at different oscillating distances and times as the first arm is rotated to cause the picking device to move linearly vertically from a supply conveyor, then to move laterally transversely, and then to move linearly vertically to deposit carried items in layers in a deep container on a second conveyor. A leveling mechanism is provided on the apparatus for maintaining the picking device in a level orientation despite oscillation of the first and second arms.

This application claims benefit under 35 USC 119(e) of provisional application Ser. No. 60/542,925, filed Feb. 9, 2004, entitled LIFT AND PLACE APPARATUS, the entire contents of which are incorporated herein in their entirety.

BACKGROUND

The present invention relates to a material-handling apparatus for lifting sets of items and placing them in layers into a container. For example, this is often used in the food industry to lift sets individually packaged food items (such as pop cans or small bags of potato chips) and place them into layers in boxes for shipping. However, the present apparatus is not believed to be limited to only this particular area.

It is known to provide an apparatus for grasping and lifting sets of packages from a supply conveyor and for placing them into containers on a second conveyor. For example, a robot with a computer-controlled arm can be programmed to do this function. However, robots are expensive to purchase and to maintain, and are not as fast and efficient as desired.

One lift-and-place apparatus that is sometimes used includes a grasping device adapted to temporarily grab a set of packages and that is mounted to a carriage. The carriage in turn is mounted on horizontal linear bearings (which keep the carriage horizontally level at all times) and further is mounted on vertical linear bearings (which allow the carriage to be moved up and down) and further is motivated by an oscillating driving arm for transporting the grasping device back and forth between a supply conveyor and a receiving conveyor. It is desirable to provide a vertical linear lift off of the supply conveyor and to provide a vertical linear drop onto the second conveyor, rather than having the carriage move arcuately at an end of the stroke of the oscillating driving arm, so that sets of items can be reliably grasped from the supply conveyor and the reason for moving vertically toward the second conveyor is so that the sets of items can be reliably/accurately placed in layers within containers without striking the vertical sides of the containers. However, it is not easy to accomplish the vertical linear lift without adding several components to the lift-and-place apparatus, which items are expensive, wear out, and have maintenance problems. Further, the added components are complex, and are unable to operate at the very high speeds desired by packaging companies.

In at least one version of such devices, the lift-and-place mechanism is provided with a grasping device that is allowed to slide longitudinally on its driving arm. The carriage is maintained in a vertical orientation by the vertical and linear bearings, and further its height is controlled by the carriage tracking along a guidance groove that extends between the supply and second conveyors. The guidance groove has vertical ends and a curvilinear crossover section, which combine to cause the grasping device to move vertically as it initially moves away from the supply conveyor, and then to move laterally to a position over the second conveyor, and then to move vertically downward to the second conveyor. The vertical ends of the guidance groove are designed to move the carriage vertically above the supply conveyor so that sets of items can be reliably grasped from the supply conveyor and to move vertically toward the second conveyor so that the sets of items can be reliably/accurately placed in layers within containers without striking the vertical sides of the containers. A problem with this type of device is that the inertia of the carriage causes substantial stress on the linear bearings and on the guidance groove, wearing them out prematurely. As the groove and linear bearings wear, the carriage begins to whip and backlash, increasing wear problems. This problem is greatly aggravated when the speed of the oscillating driving arm is increased. This problem is further aggravated when the vertical ends of the guidance groove are lengthened to allow a “deeper reach” for placing sets of items into a deeper container (i.e. a container with high side walls). It is also noted that linear bearings tend to be more expensive to purchase and maintain than rotational bearings.

Thus, a material-handling system having the aforementioned advantages and solving the aforementioned problems is desired.

SUMMARY OF THE PRESENT INVENTION

In one aspect of the present invention, a material-handling apparatus is provided for picking items from a first location and placing the items at a second location. The apparatus includes a frame, at least a pair of first arms pivoted to the frame for rotation about a first axle, and at least a pair of second arms pivoted to the first arms for rotation about a second axle. A picking device is pivoted to the second arms about a third axle. A rotational control device is operably connected to the first and second arms for oscillating the first and second arms at different oscillating distances and times to cause the picking device to move substantially vertically along a linear first path section, then to move laterally along a second path section having a large transverse component, and then to move substantially vertically along a linear third path section. A leveling mechanism is provided on the apparatus for maintaining the picking device in a level orientation despite oscillation of the first and second arms.

In another aspect of the present invention, a material-handling apparatus is provided for picking items from a first location and placing the items at a second location. The apparatus includes a first arm supported for rotation, a second arm pivoted to the first arm for rotation, and a picking device operably attached to the second arm. A control device is operably connected to the first and second arms for simultaneously oscillating the first and second arms to cause the picking device to move first linearly and then curvilinearly in a different direction with a large transverse component of movement and then linearly again. A leveling mechanism is operably connected to the picking device for maintaining the picking device in a continuous level orientation.

In yet another aspect of the present invention, a method of picking and placing items includes a step of providing a material-handling apparatus having a first arm pivoted to a frame and a second arm pivoted to the first arm and also having a picking device pivoted to the second arm. The method further includes a step of simultaneously rotating the first and second arms to cause the picking device to be moved linearly vertically away from a first conveyor, and then laterally to a position over a second conveyor, and then linearly vertically toward a container on the second conveyor; and also includes a step of maintaining the picking device in a relatively constant level position during the step of simultaneously rotating the first and second arms.

These and other aspects, objects, and features of the present invention will be understood and appreciated by those skilled in the art upon studying the following specification, claims, and appended drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of the present lift-and-place apparatus;

FIG. 1A is a perspective view of an active part of the present apparatus, including the arms, drive mechanism, and grabber of FIG. 1;

FIG. 2 is a perspective view of the first and second arms and the grasping device and the rotational control mechanism similar to FIG. 1A, but rotated to a “start” position;

FIG. 3 is an exploded perspective view of components in FIG. 2;

FIGS. 4-7 are perspective views similar to FIG. 2, but showing the apparatus in various rotated positions;

FIGS. 8A-8H are sketches showing various sets of component that interact to provide various motion control;

FIGS. 9A-9D are perspective, top, side, and front views of FIG. 1; and

FIGS. 10A-10D are side views showing the path of movement of the grabber and also rotation of the first and second arms.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present mechanism is adapted to lift sets of items from a first conveyor C1 and place the items in layers into a box or container on a second conveyor C2. For example, this is often done in the food and beverage industry. The present mechanism is very simple, yet provides for excellent control over acceleration and direction, and further provides an excellent vertical linear drop onto the second conveyor C2. It is also very robust.

The present lift-and-place mechanism 20 (FIG. 1) includes a drive shaft 21 having a first arm 22 rotatably supported on the drive shaft 21 and a second arm 23 rotatably supported by a second shaft 24 to a lower end of the first arm 22. The first arm 22 is NOT keyed to either shaft 21 or 24. A cam 25 is mounted on the second shaft 24, and both the second arm 23 and cam 25 are keyed to the shaft 24 to rotate with the shaft 24. A drive sprocket 26 is keyed to the drive shaft 21, and a driven sprocket 27 is keyed to the second shaft 24. A bicycle chain 28 interconnects the sprockets 26 and 27, so that by rotating the drive shaft 21 such as with a motor 26A, the second arm 22 is made to rotate along a selected arc.

A grabber 30 (FIG. 2) (also called a picking device herein) (such as a vacuum device for grabbing sets of individual packages or bottles off a conveyor) includes a laterally-extending remote shaft 31 that is rotatably supported on (but not keyed to) an outer end of the second arm 23. A leveling drive sprocket 32 is positioned on the second shaft 24, and a second leveling drive sprocket 33 is positioned on the remote shaft 31. A bicycle chain 34 operably interconnects the sprockets 32 and 33, so that as the second arm 23 rotates about the second shaft 24, it carries the grabber 30 with it and simultaneously keeps the grabber 30 level at all times. A stabilizer bar 40 (FIGS. 8F-8G) is pivotally supported at its top so that the bar 40 extends parallel the first arm 22. A stabilizer link 41 is pivoted to a lower end of the bar 40, and is attached to the leveling drive sprocket 32 to form a parallelogram. By this arrangement, when the first arm 22 swings back and forth, the stabilizer bar 40 and link 41 cause the leveler sprocket 32 to remain in a given orientation. Since the grabber 30 is connected by sprockets 32 and 33 and chain 34, it also stays level, even when the first arm 22 swings back and forth.

A cam 25 (FIG. 2) is keyed to the shaft 24. A pair of rollers 51 and 52 are rollingly engaged with the undulating edge 53 of the cam 25. The rollers 51 and 52 are supported in a stationary position, such as by a machine frame (not shown). As the drive shaft 21 is rotated back and forth, it causes the second shaft 24 to rotate, thus rotating the cam 25. This in turn causes the first arm 22 to swing back and forth in a selected synchronized motion with the second arm's movement and the grabber's movement.

By the above arrangement, as the drive shaft 21 is rotated, the grabber 30 is lifted from a first conveyor. The swinging movement of the first arm 21 (caused by the cam 25) in combination with the rotational movement of the second arm 23 causes the grabber 30 to initially be lifted vertically about 10 to 12 inches. The vertical movement then changes rapidly and fluidly (without sharp jolts to the grabber 30) to an arcuate lateral motion, where the grabber 30 is positioned over a second conveyor. The grabber 30 is then decelerated, and the moved vertically about 10 to 12 inches to place packages into a box or the like.

The present mechanism 20 provides a significantly greater vertical linear lift than the most-widely-used lift-and-place mechanism. (The most-widely-used lift-and-place mechanism uses linear bearings in combination with an arm that swings back and forth. The present mechanism 20 uses durable low-cost robust parts in a long-lasting arrangement where the parts will not wear out prematurely, since they will not encounter high stress. The present mechanism is very fast, reducing transfer time by as much as half.

FIGS. 8A-8H show various components and how they are coupled together to provide a desired result. FIG. 8A shows the grabber being moved while also being maintained in a continuous level position. If first arm 22 was held stationary while second arm 23 was rotated, then the grabber 30 would move along arcuate path P1. However, FIG. 8B shows the first arm 22 being oscillated back and forth on paths P2-P3 as the second arm is being rotated about a 180 degree arc. This results in a linear first path P4, transverse path P5, and linear third path P6. FIGS. 8C and 8D show the leveling mechanism that keeps the grabber level even when the second arm is rotated. FIG. 8E shows the simultaneous rotation of the first and second arms. FIGS. 8F-8G show the parallelogram mechanism that keeps the leveler sprocket and the grabber level even though the first arm swings oscillatingly back and forth while the second arm rotates about 210 degrees. FIG. 8H shows all of the motions of the first and second arms and the grabber.

FIGS. 9A-9D show the apparatus 20 from FIG. 1, but with additional detail of components and with the conveyors removed to better show the apparatus 20. FIGS. 10A-10D show the path of movement of the illustrated grabber, including linear movement from the first conveyor, curvilinear lateral movement over to the second conveyor, and linear movement toward the second conveyor. FIGS. 10A-10D also show the rotational movements of the first and second arms.

The present lift-and-place mechanism has first and second arms, a cam for controlling a swinging motion of the first arm, a chain-and-sprocket system that rotates the second arm, and a leveler mechanism for maintaining the levelness of the grabber even when the first and second arms are rotating through a complex arrangement. This arrangement of components is mechanically robust and durable, uses low-cost components in a highly effective manner for minimizing stress, maximizing speed of operation, and maximizing linear travel at ends of the movement of the grabber.

It is to be understood that variations and modifications can be made on the aforementioned structure without departing from the concepts of the present invention, and further it is to be understood that such concepts are intended to be covered by the following claims unless these claims by their language expressly state otherwise. 

1. A material-handling apparatus for picking items from a first location and placing the items at a second location, comprising: a frame; at least a pair of first arms pivoted to the frame for rotation about a first axle; at least a pair of second arms pivoted to the first arms for rotation about a second axle; a picking device pivoted to the second arms about a third axle, a rotational control device operably connected to the first and second arms for oscillating the first and second arms at different oscillating distances and times to cause the picking device to move substantially vertically along a linear first path section, then to move laterally along a second path section having a large transverse component, and then to move substantially vertically along a linear third path section; and a leveling mechanism for maintaining the picking device in a level orientation despite oscillation of the first and second arms.
 2. A material-handling apparatus for picking items from a first location and placing the items at a second location, comprising: a first arm supported for rotation; a second arm pivoted to the first arm for rotation; a picking device operably attached to the second arm, a control device operably connected to the first and second arms for simultaneously oscillating the first and second arms to cause the picking device to move first linearly and then curvilinearly in a different direction with a large transverse component of movement and then linearly again; and a leveling mechanism for maintaining the picking device in a continuous level orientation.
 3. A method of picking and placing items, comprising steps of: providing a material-handling apparatus having a first arm pivoted to a frame and a second arm pivoted to the first arm and also having a picking device pivoted to the second arm; simultaneously rotating the first and second arms to cause the picking device to be moved linearly vertically away from a first conveyor, and then laterally to a position over a second conveyor, and then linearly vertically toward a container on the second conveyor; and maintaining the picking device in a relatively constant level position during the step of simultaneously rotating the first and second arms. 